Trying to fix random failures for HistoricalTest.testRecurringPurgeIn1Run().


ReplicationTestCase.java:
In executeTask() and waitTaskState() added maxWaitTimeInMillis parameter.

HistoricalTest.java:
In testRecurringPurgeIn1Run(), added a sleep before configuring conflicts purge delay + waited purge for a maximum of 120 seconds (was approximatively 20 seconds before): as long as task max duration.

InitOnLineTest.java, ReplicationServerTest.java:
Consequence of the change to ReplicationTestCase.

GenerationIdTest.java:
Consequence of the change to ReplicationTestCase.
Extracted method createSetGenerationIdTask().